Permanent magnet fishing tool



April 15, 1958 J. H. KIRBY u PERMANENT MAGNET FISHING TOOL OriginalFiled Aug. 2, 1951 2 Sheets-Sheet 1 A a o I INVENTOR.

ATTORNEY April 1958 J. H. KlRBY n 2,830,664

PERMANENT MAGNET FISHING TOOL Original Filed Aug. 2, 1951 2 Sheets-Sheet2 INVENTOR.

Mia?

ATTORNEY United States Patent Seal PERMANENT MAGNET FISHING TOOL John H.Kirby 11, Houston, Tex.

Continuation of application Serial No. 239,901, August 2, 1951. Thisapplication February 25, 1957, Serial No. 641,949

The portion of the term of the patent subsequent to February 2, N71, hasbeen disclaimed 6 Claims. (Cl. 166-65) The invention relates to a welltool which is particularly adapted for the recovery of junk from a wellbore, generally known as a fishing tool.

This application is a continuation of my prior application Serial Number239,901, filed August 2, 1951, now abandoned.

In the drilling of wells by the rotary method a drill bit is rotated andlowered into the well bore by means of a string of drill pipe, and suchwells are sometimes drilled to a depth of ten or fifteen thousand feet,and only recently a well has gone to twenty thousand feet.

It is only natural that a drill bit or other tools in such a well boreare subjected to a great deal of vibration and agitation, and thevarious parts or elements thereof become loosened and drop, or are leftin thewell bore in such a manner as to interfere with the furtherdrilling of the bore.

In connection with the present application, the invention will bedescribed for the purpose of the recovery of such junk or fish from thewell bore, and the present drawings illustrate three of the cones whichhave come loose from a standard type of rotary rock drilling bit wherethe cones are mounted on short stub shafts and caused to cut the bottomof the well bore.

it is important that such cones be recovered from the well bore beforethe drilling may be resumed.

it is one of the objects of the present invention to provide a fishingtool with a permanent magnet of a particular type whereby the magneticfield of such magnet is moved into a position such as will attract thefish with the resultant recovery of the fish from the well bore.

Another object of the invention is to provide a fishing tool hollowbody, in which the permanent magnet is mounted with an annular spacetherearound so that it may be possible to set up a reverse flow ofliquid upwardly through the tool.

Another object of the invention is to provide a permanent magnet fishingtool wherein a reverse flow of liquid and the magnetic attraction of thefish tend to cooperate together to accomplish much lifting action.

Another object of the invention is to provide a permanent magnet fishingtool in which a stream of liquid may be discharged downwardly throughthe tool and the direction of such flow reversed, so that there will bea tendency to lift the fish or junk and raise it for attraction V overwhich a tool may be lowered to cause a relative movement between thetool and the magnet, which will in turn affect the volume of how ofliquid through the tool as an indication to the operator that a piece ofjunk has been recovered by the tool.

A still further object of the invention is to provide a Patented Apr.15%, li hts permanent magnet fishing tool with an expansible packingwhich will tend to create a seal between the periphery of the tool andthe well bore, so as to cause the circulation of liquid to returnupwardly through the tool so as to facilitate the junks recovery by thecombination of the flow of liquid and the attraction of the magnet.

Still another object of the invention is to provide a permanent magnetfishing tool wherein the magnet is caused to slide in the tool byengagement with the fish and wherein further such sliding action afiectsthe volume of flow of the circulating liquid so as to indicate to theoperator by such change in volume of flow that the fish has beenrecovered.

A still further object of the invention is to. vary the flow of liquidthrough a permanent magnet fishing tool as a function of the size,amount, or number of pieces of junk which have been recovered.

Other and further objects of the invention will be readily apparent whenthe following description is considered in connection with the.accompanying drawings, wherein:

Fig. 1 is a vertical sectional view taken on line 1-1 of Figure 2showing a permanent magnet fishing tool wherein the circulation of theliquid acts in combination with the magnetic attraction to recover thejunk in the tool and wherein further there will be a movement of themagnet as a function of the junk recovered.

Fig. 2 is a sectional view taken transverse of the tool of Fig. 1 uponthe line 2-2 and looking in the direction of the arrows of Fig. 1.

Fig. 3 is a vertical sectional view of a slightly modified form of thepermanent magnet fishing tool; and

Figs. 4, 5, and 6 are horizontal sections taken on lines 44, 5, and 66,respectively, of Figure 3.

The most simple form of the invention is seen in Fig. 1 wherein isillustrated well bore 2 drilled by the rotation of a bit by the rotarymethod of drilling wells.

Such drill bits have movable elements thereon such as the cones whichare mounted to engage the base 3 of such well bore 2 and to cut thebore.

It will be understood that an abrasive drilling mud or liquid is pumpeddown through the drill pipe and is discharged at the bottom of the boreto cool the bit and carry away the cuttings. This abrasive material incombination with the rotation and the pressures applied often result inthe loss of the cones 4 from the drill bit. If such a cone, known as apiece of junk, remains in the bottom of the well bore it, of course,interferes with the future drilling operations, and it is desirable torecover such a cone or piece of junk with as little delay and cost aspossible. In the drawing in Fig. 1 three such cones 4 have beenillustrated as having been lost in the well bore.

The present tool comprises a body designated generally at 10 andincluding a neck 12 which is hollow in form and of a size to be loweredinto the well bore by being threaded at 14 to a string of pipe. Thepassage 15 extending into the neck 12 accommodates a flow of drillingliquid as is well known in the art.

The body 10 is enlarged at 16 so that it closely approaches the size ofthe Well bore 2. The lower end of such body is also hollow at 18 as willbe described.

A partition means 19 to be described in moredetail hereinafter extendsacross the passage 15 so as to cause the flow of drilling liquid to movelaterally through the openings 20, a number of which have been provided.In this manner the cross-sectional area of the passage 15 isapproximated by the cross sectional area of the plurality of passages20.

The wall 21 of the side of such body is provided with the verticalpassages 22 communicating with passages 20 to accommodate the dischargeof the flushing liquid downwardly through the fishing tool. The passages22 are formed by vertical grooves in the inner face of wall 21 (seeFigure for the same construction in the other form of the invention),the grooves being covered by an inner sleeve which may be made of aplurality of rings 49 resting on base ring 41. The flushing liquid willpass through the passages 22 and the inwardly directed pas sages 23 inbase ring 41 so as to discharge at 24 below the tool in an inwarddirection. Inasmuch as the space 25, constituting the lower end of thewell bore below the tool, is a substantially closed area, the dischargeof this liquid at 24 reverses its direction and moves upwardly throughthe openings 30 in pole plate 41' into the space 31 which is an annularspace inside of the wall 21 of the body of low carbon steel.

The upfiow of liquid may discharge from the space 31 through outlets 32in body into the annular space 34 in the well here around the body 10.

From the foregoing it will be apparent that there will be a tendency ofthe flow of liquid discharging at 24 to lift the cones or junk 4 to asubstantial extent because of its reversal of direction.

This flow of liquid is one source of power for setting the tool on thejunk 4.

The present tool body 10 carries therein a permanent magnet 35 which isof an elongated construction, with the upper end of such magnet 35disposed in neck 12. With a magnet so positioned, and the north pole atthe upper end, the south pole 40 will, of course, be at the lower oropposite end of the magnet from the north pole.

The base ring 41 cooperates with pole plate 41' at the bottom of themagnet 35 to support the south pole 40 of the magnet laterally andretain it in centralized position relative to wall 21. It will beappreciated that, as pointed out in more detail hereinafter, the magnet35 is movably disposed within body 10 with plate 41 being slidablerelative to base ring 41 as a support for the south pole 40 of themagnet. This plate 41 may be recessed at 42 to receive the end 40 of themagnet to which it is suitably secured and there may be the openings 30through the outer part of the plate which is insulated from the balanceof the plate by the non-magnetic circular ring 45. In this manner therewill be no grounding or shorting of the magnet across the plate 41.

In normal operation with a magnet thus disposed the lines of flux willextend between the north pole 37 and the south pole 40 along thewalls21.

Because of the non-magnetic portion of the plate 41' there willtherefore be setup an external magnetic field across the bottom of thetool where the lines of flux pass into the south pole 40 radiallythrough the base ring 41 from the walls 21. ,In this manner the uppercone or piece of junk 4 will be present in the magnetic field of themagnet when the tool is lowered to the position shown in Figure 1. Sucha piece of junk 4 will be attracted in this manner so that it may belifted and removed from the well bore. The base ring 41 around plate 41will be held in position by the rotary shoe 46 which is threaded at 47onto the lower end of the wall 21 of the tool. A seal ring 48 may beprovided if desired.

The magnet 35 is of a construction which is now marketed under the tradename Alnico V. Such magnets may consist of the combination of cobalt,aluminum, nickel, and iron. Such a magnet may have a capacity of pickingup 500, 1,000, or even 2,000 pounds, which considered ounce for ouncewith previous magnets may approximate 24 times prior known magnets. Suchmagnets also are known to have a resistance to demagnetization which is8 times the resistance of other previous known magnets. A reference to amagnet made of a platinum alloy which is also suitable for use in thepresent tool may be found in Quick Magazine of May 28, 1951, at page 47,where it is indicated that such a magnet is manufactured bylGeneralElectric Company.

-of the non-magnetic spindle.

Improvements in such magnets have also been made Where the magnetincludes platinum and cobalt.

In actual operation the tool may be connected to a pipe at 14 andlowered into the well bore with a view of moving the magnetic field atthe lower end of the tool closely adjacent the south pole of the magnetinto a position in which to attract the fish or junk.

In order to encourage the circulation of liquid down through the pipeand inwardly through the tool to assist in recovering the junk a packermember 50 is shown as having been arranged circumferentially about thetool so that the packing element extends radially suificient to contactthe wall of the well bore. Such a packer would normally tend to expandand prevent a return flow of liquid upwardly around the drill bit, butsuch prevention is enhanced by the arrangement of the small openings 51through the wall 21 from the passages 22 so that there will be a liquidpressure applied inside of the packing element to assist in effecting aseal around the outside of the tool.

Under such circumstances there will be a complete reversal ofcirculation at the bottom of the tool so as to assist in lifting thejunk.

It is desirable to be able to tell when the tool has engaged a piece ofjunk. To this end the passage 15 has been enlarged at 70 and has beenfitted with a hollow sleeve 71. A seal is formed about this sleeve at 72by an O-ring.

This sleeve is threaded at 74 into the base 75 'of the upper end of thetool, and such sleeve will be positioned in leak-proof condition by theassembly of the parts.

There are a plurality of ports annularly disposed in sleeve 71 ataplurality of vertically spaced levels, such as ports forming an upperring of ports and ports 81 forming a lower ring. When there is a flow ofliquid down through the passage 15 this flow of fluid may move outthrough the ports 80, 81 in the sleeve 71 and discharge into theenlarged area 70 and thence through the passages 22 down through thesidewall 21 of the enlarged portion of the tool.

Before completing the description of the means for indicating at thesurface when a piece of junk has been engaged, the Figure 3 embodimentof the invention will be described. The embodiment of the tool shown inFigures 3-6 is largely the same as that shown in Figures :1 and 2 exceptfor the magnets. The annular space 31 is the same in Figure 3 as Figure1 except that there has been provided a non-magnetic spindle 85 which isslidably arranged in such annular space rather than having a bar magnetso positioned as in the construction of Figure 1.

This non-magnetic spindle 85 is arranged with a head 86 and a lateralcutaway 87 on which is disposed a magnet 35' in the shape of a ringhaving a slot 89 thereacross. The position of the magnet 35' dependsupon the sliding The magnet is thus suspended in the lower portion ofthe tool recess closely adjacent the lower end thereof.

Generally, this construction is similar to that of Figure 1 except thatthe magnet 35' is mounted on the mandrel 85 which is movable verticallyof the tool.

The upper end of the spindle 85 is disposed above the stop ring 92 andmay have the sealing cup 93 held thereon by cap and screw 96 so as toinsure a seal between the spindle and sleeve 71. A seal may also beprovided between base 75 and the upper end of annular magnets 49. Thesame construction is used in the embodiment of Figures 1 and 2 to sealthe upper end of magnet 35. This is the partition means 19 previouslyreferred to.

It seems obvious, therefore, that in both embodiments of the inventionwhen the tool is lowered into the operating position that the magnetwill be in the lowermost position shown and will exert a magnetic forceupon the junk or cones 4, tending to lift them into the tool.

asa eea In event, however, that the tool is lowered over a piece of junksuch as the cone 4 the magnet will engage the cone or fish and thecontinued lowering action of the tool will cause the cone to stop thedownward movement of the magnet 35 or 35 whereas the tool continuesdownwardly. In this manner the sleeve 71 will be telescoped over theupper end of the magnet or spindle to such an extent that it will coverthe ports 81 and choke oil at least a part of the discharge of liquid.This choking off will be an indication to the driller that there hasbeen a restriction of circulating liquid and an indication that a pieceof junk has been encountered and picked up. In some instances continuedlowering action may raise the packing 93 above both rows of openings orports to such an extent that there may be a complete shut off of thecirculating liquid.

Such a shut off will be readily apparent to the driller and anindication to him that he has recovered one or more pieces of junk andthat he should withdraw the tool to the surface to recover the junk.

It seems obvious that both embodiments of this tool are very similar,that the magnet is applied in an efficient manner and that the inventionbroadly contemplates the combination of a permanent magnet and thecirculation of liquid in the well to exert a combined lift on the junkor fish.

I claim:

1. A permanent magnet fishing tool comprising a pair of coaxiallydisposed members providing inner and outer radially spaced portions, theouter portion being of tubular form with at least a part thereof beingmagnetic material, the inner portion being of elongated form with atleast a part thereof being magnetic material, said inner portionincluding a permanent magnet, said outer portion providing an annularmagnetic pole at the lower end of said outer portion surrounding saidinner portion, and a body connecting said inner and outer portionstogether,

said body having means thereon for connecting the tool to conduit meansfor raising and lowering the tool in a well and thereby to a source offluid under pressure to conduct fluid through the annular space betweensaid inner and outer portions, means slidably mounting said innerportion relative to said outer portion whereby the lower end of saidinner portion is moved up above the lower end of and inside said outerportion on application of force to the lower end of said inner portion,and a rotary shoe removably secured to the lower end of said outerportion.

2. A well tool for the recovery of junk in a well bore drilled by therotary method comprising a hollow body, a hollow neck on the upperportion of said body having a connection thereon for a pipe, a permanentmagnet disposed in said body with its north pole upper end in the hollowportion of said neck, said body including inner and outer walls, saidinner wall defining the outside of a fluid flow space from the lowerpart of and out through said body around said magnet, for the up flow ofliquid to assist in the recovery of junk, said body having passage meansextending from said fluid flow space to the outside of said body, a basefor said body including a support for the south pole of said magnet. anon-magnetic member about such south pole, and down flow passages fromthe upper end of said body between the walls of said body andcommunicating with said hollow neck to discharge liquid outwardly fromsaid tool to flow around the junk in the well to wash the junk upwardlytoward and to be attracted by said magnet, said magnet being movablydisposed in said hollow body.

3. A well tool for the recovery of junk in a well bore drilled by therotary method comprising, a hollow body, a hollow neck on the upperportion of said body having a connection thereon for a pipe, a permanentmagnet disposed in said body with its north pole upper end in the hollowportion of said neck, said body including inner and outer walls, saidinner wall defining the outside of a fluid flow space from the lowerpart of and out through said body around said magnet, for the up flow ofliquid to assist in the recovery of junk, said body having passage meansextending from said fluid flow space to the outside of said body, a basefor said body including a support for the south pole of said magnet, anon-magnetic member about such south pole, and down flow passages fromthe upper end of said body through the wall of said body andcommunicating with said hollow neck to discharge liquid outwardly fromsaid tool to flow around the junk in the well to wash the junk upwardlytoward and to be attracted by said magnet, said magnet being movablydisposed in said hollow body, and a portion on said magnet in said neckto reduce the inlet of liquid from the upper end of the tool as anindication that junk has been recovered.

4. A well tool for the recovery of junk in a well bore drilled by therotary method comprising, a hollow body, a connection at the upper endthereof for a pipe, inlet means placing said connection in communicationwith the interior of said hollow body at the upper end thereof, anon-magnetic spindle having at its lower end a permanent magnet disposedin said body and with its upper end in the hollow portion of said body,a fluid flow space extending from the lower part of said body aroundsaid magnet up around said spindle and out through said body for the upflow of liquid to assist in the recovery of junk, a base for said bodyaround the outside of said magnet, and down flow passages from the upperend of said body through the wall of said body to discharge liquid toflow around the junk in the well to wash the junk upwardly toward and tobe attracted by said magnet, said magnet carrying spindle being movablymounted in said hollow body for axial movement upwardly in the samedirection as the fluid flow past the magnet.

5. A well tool for the recovery of junk in a well bore drilled by therotary method comprising, a hollow body, a connection at the upper endthereof for a pipe, inlet means placing said connection in communicationwith the interior of said hollow body at the upper end thereof, anon-magnetic spindle having at its lower end a permanent magnet disposedin said body and with its upper end in the hollow portion of said body,a fluid flow space extending from the lower part of said body aroundsaid magnet up around said spindle and out through said body for the upflow of liquid to assist in the recovery of junk, a base for said bodyaround the outside of said magnet, and down flow passages from the upperend of said body through the wall of said body to discharge liquid toflow around the junk in the well to wash the junk upwardly toward and tobe attracted by said magnet, said magnet carrying spindle being movablymounted in said hollow body, and a means on said magnet carrying spindleat the upper end of the spindle cooperating with means in said inletmeans to form a valve actuated in the closing direction by upwardmovement of said spindle to reduce the inlet of liquid from the upperend of the tool as an indication that junk has been recovered.

6. A permanent magnet fishing tool comprising a pair of eoaxiallydisposed members providing inner and outer radially separated portions,the outer portion being of tubular form with at least a part thereofbeing magnetic material, the inner portion being of elongated form withat least a part thereof being magnetic material, said inner portionincluding a permanent magnet, said outer portion providing an annularmagnetic pole at the lower end of said outer portion surrounding saidinner portion; a body including an upper hollow portion having means onits upper end for connecting the tool to conduit means for raising andlowering the tool and thereby to a source of fluid under pressure, and alower hollow portion having means at its lower end projecting inwardlyto form a support and downwardly to provide teeth; said lower hollowportion surrounding said outer portion, the upper end of said lowerhollow portion being connected to the lower end of said upper hollowportion, said outer portion being held against axial movement onlybetween said support at its lower end and the lower end of said upperhollow portion, and fluid passage means between said outer portion andsaid lower hollow portion communicating at the upper end thereof withthe interior of said upper hollow portionand at its lower end with thebottom exterior of the tool.

References Cited in the file of this patent UNITED STATES PATENTS AthyNov. 25, 1947 Murphy et a1 Jan. 10, 1.950 Noble Sept. 12, 1950 Nolley eta1 June 12, 1951 Paysinger Jan. 15, 1952 Hawkins Oct. 14, 1952 Fast Dec.7, 1.954

